These four films are:
SHERLOCK HOLMES AND THE SECRET WEAPON (1943)
SHERLOCK HOLMES - THE WOMAN IN GREEN (1945)
SHERLOCK HOLMES - TERROR BY NIGHT (1946)
SHERLOCK HOLMES - DRESSED TO KILL (1946)
Of the 4 public domain films (or all 14 for that matter), THE WOMAN IN GREEN is a key film in that the arch-enemy of Holmes, Professor Moriarty, finally gets his just due.

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